Coating out of gelatin layers



and the product produced thereby.

facilitating coating procedures or operations.

' "Other-ebjectswill appear herein.

United States Patent '07 COATING OUT OF GELATIN LAYERS William J. Knox, Jr., and William F. Fowler, Jr., Rochester, N. Y., assignors to Eastman Kodak Company, Rochester, N. Y., a' corporation of New Jersey No Drawing. Application December 29, 1955 Serial No. 556,044

11 Claims. (Cl. 9694) This invention relates to an improved coating procedure In particular this invention concerns an improved process for coating photographic materials onto a base such as film base or paper base to produce an improved photographic product.

There are many instances in industry where it is desired to apply one or more relatively thin coatings or layers to various type bases. In the photographic industry particularly products are prepared by applying relatively thin coatings to various types of bases such as film and paper bases. It is usually desirable that those coatings be relatively uniform and that the coated base be free of bare spots or other imperfections. It is also desirable to apply such coatings at goodproduction speeds for efiiciency of operation.

In the coating of photographic film or paper with a r-gelatinlayer such as of a photographic emulsion or of other desired compositions an even coating must be obtained. In the absence of 'a coating aid numerous small crescent shaped uncoated areas are observed in the final product. These defects are about the size of a pin head with streaks running from the points of a crescent in a direction opposite to that of coating. Sometimes lightly coated areas from 5'l0'rn'm. in diameter 'may'a'lso appear.

It has already been suggested-inthe arm utilizevario us surface active agents in gelatin coating compositions for Saponin has been used for this purpose and eliminates many of the defects in coating, giving a uniformly even coating partcularly where the gelatin-layer is applied to a dried surface. Saponin, however, is a naturally occurring material of vegetable origin andmay vary markedly from batch to batch in quality as well as in composition. The quality of some batches of saponin may cause an increase in fog or a decrease of sensitivity of certain emulsions or may even result in no improvement in the coating properties of the composition to which it is added. These wide variations in thequality of this :natural mat'erial make preferable as coating aids surface active agents which are reproducible from batch to batch both'in chemical'composition and behaviour. A number of synthetic agents have utility for coating'pur'poses but they are often deficient in some respect. For example, certain coating aids naturally contribute to the ease of co'atingbut they are "not useful because of adverse photographic properties.

Various'o'ther difiic'ulties and problems arise in the photographic industry in the application of gelatin layers to a support.

This invention has for one object to provide an improved method for applying aqueous gelatin coatings. I Another object of our invention is toprovide a method for applying gelatin coatingsin the preparation of photo- --graphic materials in which the coatings which result are uniformly even and repellency free and which are photographically inert. A further'object of our invention is to prepare coatings from aqueous gelatin compositions.

Weaave foundthat-ce'r'tain materials like the salts of residue was dissolved in distilled water.

2,823,123 Patented Feb. 11, 1958 ICC owmcngonconnon-coorr X where R is hydrogen or an alkyl of at least 5 carbon atoms (such as 5-18) at least one R being alkyl and the total number of carbon atoms in the R groups being at least 10.

X =CH or COOM M =alkali metal substituent n=a number in the range 1-12.

The ratio of maleopimarate to the above identified salt should be within the range 36:1 to 5:3 of the former to the latter.

One of the most useful compounds of the type illustrated is disodium N-(carbo-p. tert octyl phenoxy-pentethoxy) glutamate. Compounds of this type can be prepared by reacting an alkyl aryloxy polyethoxy ethanol having the formula:

nv being 1-12 and R being hydrogen or an alkyl of at least 5 carbon atoms at least one R being alkyl with an isocyanate ester having the formula: OCN-CHR-COOR" in which R may be for example CH COOR",

and the like and R" may be ethyl or other lower alkyl, which reaction is followed by treatment with a base such as NaOH to obtain sodium or some other salt thereof.

The following example is illustrative of the general procedure of preparing these compounds. These compounds and their preparation are not our invention but is the invention of WilliamJ. Knox, Jr., and Charles V. Wilson Serial No. 600,679, filed July 30, 1956:

A mixture of 22.5 g. of dimethyl isocyanato glutarate and 47.5 g. (1 molar equivalent) of p-tert. octyl phenoxy tetraethoxy ethanol was heated at 8090 for three hours. The resulting product was dissolved in alcohol and 9 g. (2 molar equivalents) of NaOH dissolved in a little water was mixed therewith. The mass was heated at 65 C. for one hour. The solvent was removed and the pasty When a shorter chaincompound such as p-tert. octyl phenoxy ethanol or p-tert. octyl phenoxy diethoxy ethanol is employed as the starting material, the sodium salt separates as a solid and A can be separated by filtration.

gelatin or as photographic emulsions which are ordinarily comprised of'an aqueous solution'of gelatin containing as 200 ml. of 28% aqueous ammonia. 'othermic reaction occurs and the acid dissolves therein.

the light-sensitive material a silver salt such as silver chloride, silver bromide, silver iodide or their mixture. The emulsion may contain other added materials such as sensitized dyes, hardeners or the like. Descriptions of photographic emulsions are found in the prior art such as in Fundamentals of Photographic Theory by James and Higgins, published in 1948 by John Wiley and Sons, chapter 2.

The following examples illustrate the preparation of materials which are useful as coating aids.

Example 1 100 grams of maleopimaric acid were suspended in On stirring, an ex- Example 2 50 grams of maleopimaric acid were suspended in 300 ml. of water and 93.8 ml. of 4 normal NaOH were slowly added thereto thus producing a very hazy solution having a pH of 11.5. The sodium salt thus obtained was precipitated into a liter of acetone, washed repeatedly with acetone and dried in the air. 52 grams of a completely water-soluble sodium maleopimarate were obtained.

Example 3 Mono, di and tri-ethanolamine salts of maleopimaric acid were obtained by preparing homogeneous solutions in the following proportions:

(A) 40 grams maleopimaric acid; 20 grams ethanolamine and 100 ml. of distilled water.

(B) 40 grams maleopimaric acid; 35 grams diethanolamine and 100 ml. of distilled water.

(C) 40 grams maleopimaric acid; 50 grams triethanolamine; and 100 ml. of distilled water.

Prior to use the above preparations may be diluted with distilled water if desired.

The base to be coated with a gelatin layer may be composed of any of the usual conventional film base materials. This may be a sheeting of a cellulose ester such as cellulose nitrate or an organic acid ester of cellulose such as cellulose acetate, cellulose acetate propionate or cellulose acetate butyrate. It is often desirable to apply first a subbing layer to the cellulose ester base to contribute to the adhesiveness of the gelatin coating layer thereto as is well known in the art. As for the use of a paper base, that material is usually first coated with barium sulfate in suspension in a colloid such as gelatin prior to the application of a photographic emulsion or similar gelatin layer. A description of photographic paper is found in Kodak Data Book, 5th edition,

. Kodak Papers, pages 3 and 4.

The coating procedure utilized may comprise any of I the standard procedures employed in the industry. For

' Serial No. 489,862, T. A. Russell, February 23, 1955.

Serial No. 489,969, ,Mercier et.al., February 23, 1955.

4 Serial No. 489,863, T. A. Russell, February 23, 1955. Serial No. 489,861, T. A. Russell et al., February 23,

We have found that by incorporating a water soluble maleopimarate in a gelatin coating composition the coating of that composition on a support therefor is facilitated and a high quality uniform coating is obtained. In incorporating a coating aid as described herein it is usually desirable to add it in the form of dilute aqueous solution such as of 2% concentration. In this manner uniform distribution of the coating aid in the coating composition is obtained. The following examples illustrate our invention:

Example 4 There was incorporated in a silver halide gelatin emulsion, ammonium maleopimarate in the concentration of 0.5 gram thereof per pound of emulsion. The coating was-applied to a paper support. Also employed was a sample of the emulsion without coating aid therein. The following results were obtained:

Ooncentra- Photo- Goating Ald tion, grams Repellency graphic per pound Properties Ammonium maleopimarate 0.5 1 0. K. None None 15 0. K.

Example 5 A coating procedure was carried out similar to that described in Example 4 except that monoethanol amine maleopimarate was employed as the coating aid. The results obtained were as follows:

Concentra- Photo- Coatmg Aid tion, grams Repellency graphic per pound Properties Ethanolamine maleopimarate. 0. 5 5 0. K. N one None 8 0 K.

Example 6 A procedure similar to that described in Example 4 was carried out but using triethanol amine maleopimarate. The results obtained were as follows:

Concentra- Photo- Ooating Aid tion, grams Repellency graphic per pound Properties Triethanol amine maleopimarate. 0. 5 0 0. K. None; None 8 O. K.

Example 7 A procedure similar to that described in Example 4 but using a sodium maleopimarate as a coating aid was A gelatin coating was applied in .the same manner as I described inExample 4 but using diethanol amine male- 5 opimarate coating aid. The following results were obtained:

Coatings similar to those described in Example 4 but involving sodium maleopimarate concentrations varying from 0.25 to 1 gram per pound were carried out. The following results were obtained:

' Goncentra- Photo- Coating Aid tlon, grams Repellency graphic per pound Properties 6 O. K. 0.25 0 O. K. 0.50 0 O. K. 1.0 0 O. K.

Example 10 In an application of a silver halide-gelatin photographic emulsion topaper sodium maleopimarate was employed as a coating aid at concentrations of from 0.14-1.2 grams per pound of wet emulsion. The following results were obtained:

Example 11 To a photographic silver halide X-ray emulsion was added a mixture of sodium maleopimarate and disodium N(carbo p tert.-octy1phenoxypentaethoxy)glutamate (36:1) the ratio by weight of total coating aid to emulsion composition was 1 gram per 2.5 lbs. of emulsion. The emulsion was then coated upon a support thereof. There was also applied an overcoating of a gelatin solution containing a similar coating aid in the proportion of 1 gram per 7.7 lbs. of coating composition. It Was found that the coating operation proceeded even better than is obtained by using only sodium maleopimarate as the coating aid.

Example 12 To a series of emulsions were added mixed coating aid as described in the preceding example, the ratio of sodium maleopimarate to the auxiliary material being 10:1, 9:1, :1, 5:2, and 5:3 respectively. In all cases the coating results obtained were excellent and no serious coating diificulties were observed.

Example 14 In an air-knife coating of an 8% gelatin photographic emulsion in which a mixture of sodium maleoprimarate s and disodium N-(carbo-p tert-octylphenoxypentaethoxy) glutamate in the ratio of 5:1 was added the following results were obtained:

Concn Repel- .Photo- Surfactant g./lb 'lencies graphic :per 7.5'tt. Properties Blank 10 0. 'K. Mixture" 0. 13 1 O. K. Mixture 0. 5 2 O. K. Mixture 1. 0 0- 0. 'K.

In addition to being a wet-on-dry coating agent, 'tli'is mixture was found to have excellent high-speed wet-o'n-wet coating properties. The drying surfaces of the gelatin coatings made with this mixture as a coating aid are-not Example 15 In a coating experiment similar to the preceding example the two surfactants were mixed in theratio of 10:1 and were added to the gelatin coating composition; repellencies on the same order in the proceeding example as were obtained. Also this coating aid mixture'facilitated high-speed wet-on-wet coating with gelatin coating compositions.

One advantage of this mixed composition coating aid over coating aids having but a single material is that objectionable mottlingis' avoided while in some instances using but a single compound as a coating aid mottling of the coating applied may occur. These mixtures in addition have the advantage of being eflective coating aids in a wide variety of coating techniques.

Example 16 An aqueous solution of gelatin comprising 39 grams of gelatin per pound of coating solution to which a magenta dye had been added was divided into three parts. To one was added 0.25 grams of sodium maleopimarate per lb. of gelatin solution and to another the usual concentration of saponine; the third part was employed as a check. The compositions were each applied as thin layers to cellulose triacetate film base by dip coating. Inspection of the coatings while still wet showed no repellencies in 25 square feet of the sodium maleopimarate coating, 3 repellencies with the saponine coating and 13 repellencies with the gelatin layer containing no wetting agent.

Example 17 A gelatin-silver halide X-ray emulsion which comprises 26 grams of silver halide and 33 grams of gelatin per pound of coating solution was supplied with 0.4 gram of sodium maleopimarate per pound of emulsion. This emulsion was then coated out onto a subbed cellulose triacetate support. The product was inspected while still wet and the coating was found to be uniform and entirely free of repellencies.

Emulsion coatings such as are applied in accordance with our invention may be tested for repellency spots or coating defects by exposing the coating to a carbon arc light which light points out the emulsion having darkened coated areas and emphasizing the bare repellency spots. The number of spots counted in a given area as compared with the spots obtained when treating standard coatings in this manner gives an indication of the repellency present in the coating being tested. Ordinarily in coatings in accordance with our invention in an area of 10 square feel it is only occasionally that any repellency spots are observed and then only on the order of one whereas with otherwise identical coatings in which a coating aid is not employed several spots may appear.

-.l. In a method of coating in which gelatin coating compositions are applied to a support, the step which comprises adding to the gelatin coating composition a watersoluble maleopimarate salt in the proportion of 0.1 to 1 gram per pound of coating composition.

2. In a. method of applying coatings to a support in which an aqueous dispersion of gelatin is applied as a thin layer to the support, the step which comprises adding to the gelatin coating composition a coating aid the major proportion of which is sodium maleopimarate.

3. In the applying of gelatin layers to a surface, the step which comprises adding to the gelatin coating composition prior to applying to the surface a small proportionof a mixture of a water-soluble maleopimarate and the hydrolyzed-reaction product of an alkyl aryloxy polyethoxy ethanol and an isocyanate ester.

4. A composition comprising an aqueous solution of gelatin containing therein a surface active agent the major proportion of which surface active agent is a watersoluble maleopimarate.

5. A photographic -gelatin-silver halide emulsion containing therein as a coating aid a surface active material the'major proportion of which surface active agent is a water-soluble maleopimarate.

6. An aqueous solution of gelatin containing 0.1 to 1 ,gram of sodium maleopimarate per pound of composisolution of gelatin containing therein as a coating aid a small proportion of a mixture of a water-soluble maleopimarate and a compound having the formula:

8. A composition of matter comprising an aqueous solution of gelatin containing as a coating aid therein a small proportion of a mixture of sodium maleopimarate and N- (carbo-p-tert-octylphenoxypentaethoxy) -glutamate.

9. A photographic product comprising a support having thereon a layer of gelatin containing an alkali metal j maleopimarate.

10. A photographic'product comprising a supporthaving thereon a layer of a gelatin-silver halide emulsion containing an alkali metal maleopimarate.

11. A photographicproduct comprising film base having thereon a layer of a gelatin-silver halide emulsion containing an alkali metal maleopimarate.

References Cited in the file of thispatent UNITED STATES PATENTS 2,713,539 Fowler et al. July 19, 1955 

1. IN A METHOD OF COATING IN WHICH GELATIN COATING COMPOSITION ARE APPLIED TO A SUPPORT, THE STEP WHICH COMPRISES ADDING TO THE GELATIN COATING COMPOSITION A WATERSOLUBLE MALEOPIMARATE SALT IN THE PROPORTION OF 0.1 TO 1 GRAM PER POUND OF COATING COMPOSITION. 